fix: tidy code and update endpoints

packages/lib/server-only/share/get-recipient-or-sender-by-share-link-slug.ts

@@ -0,0 +1,42 @@
+import { prisma } from '@documenso/prisma';
+
+export type GetRecipientOrSenderByShareLinkSlugOptions = {
+  slug: string;
+};
+
+export const getRecipientOrSenderByShareLinkSlug = async ({
+  slug,
+}: GetRecipientOrSenderByShareLinkSlugOptions) => {
+  const { documentId, email } = await prisma.documentShareLink.findFirstOrThrow({
+    where: {
+      slug,
+    },
+  });
+
+  const recipient = await prisma.recipient.findFirst({
+    where: {
+      documentId,
+      email,
+    },
+    include: {
+      Signature: true,
+    },
+  });
+
+  if (recipient) {
+    return recipient;
+  }
+
+  const sender = await prisma.user.findFirst({
+    where: {
+      Document: { some: { id: documentId } },
+      email,
+    },
+  });
+
+  if (sender) {
+    return sender;
+  }
+
+  throw new Error('Recipient or sender not found');
+};